Studies On Structure Of Zooplankton Community In The North Canal Downstream Wetland

Dahuangpu wetland natural conservation located at east Wuqing zone was established at September 30,2005, which was crossed by four rivers. The climate here was suitable for reedmarshes.As a major primary consumer, Zooplankton serves as both an important biological indicator and food of fishes living in up-middle-waters. The community of zooplankton whose variation in species and quantity greatly indicates the change of water quality is one of the main communities in pools.The study on zooplankton community structure was carried out via consecutive sampling at Dahuangbu wetland natural conservation from March to October 2010. Based on the wild investigation, the relationship between zooplankton community structure and environmental factors was analysed, furthermore, ecological assay of present water quality was done. Thus, this research provides important biological data on environmental monitoring, management and protection when refer to the downstream wetland of Beiyunhe River.Main results as follows:1. The composition of zooplankton: 55 species of zooplankton were classified including 35 Rotifera (63%) distributed in 3 suborder, 10 family, 17genus; 12 Cladocera (22%) total 5 family and 7 genus; 8 Copepoda (15% without nauplius) total 2 order, 4 family and 8 genus. Species were less in spring and increased in summer and fall at the wetland natural conservation.2. Seasonal variation: zooplankton species were least on March (6 species) in accordance with zooplankton quantity (2512ind/L) and largest on June with most quantity on may (7843ind/L). Rotifera species showed more differences among months that most on May least on March with low ebb on July. Cladocera fluctuated little in general but decreased in July. Most Copepoda occurred on August. Species of Cladocera together with Copepoda increased in summer and fall and decreased in spring due to mainly changed in temperature without ruling out pH, DO, nutritive salt, and human activity.3. Dominant and common species: Dominants contained mainly species of middle tolerance value as Brachionus calyciflorus and Cycolops vicinus. Fastigium of dominants occurred with different area. There were 9 common Rotifera and one common species Cladocera,.2 common species Copepoda.4. Relationship between zooplankton and environmental factors: The present study indicated an important relation between quantitative variation, species, distribution and environmental factors. The fact that species increased with the rising temperature showed an influence impact of water temperature on zooplankton. pH around 8.4 was the best suitable for zooplankton in Dahuangpu. Species increased as the rising of DO with exceptional months, which indicated that DO was not the main effective factor for the changes of zooplankton.5. Biodiversity index and assay of water quality: Water quality was in light and moderate pollution at all sampling sites in the whole year, even heavy pollution on May and July except for siteⅠon May and siteⅣon August as a result of the Shannon-Wiener index. Margalef index indicated that water in the wetland was at a level ofβ-moderate pollution to heavy pollution.